diff --git a/.luacheckrc b/.luacheckrc
new file mode 100644
index 0000000..b557738
--- /dev/null
+++ b/.luacheckrc
@@ -0,0 +1 @@
+std="love+luajit"
diff --git a/TODO b/TODO
index 4ef844e..33fc816 100644
--- a/TODO
+++ b/TODO
@@ -3,6 +3,13 @@
 [x] Add Entity:ensure (maybe?)
 [ ] Put pools in the Instance and invert dependency.
 [ ] Share pools between systems
-[ ] Remove System callbacks
+[x] Remove System callbacks
 [x] Put .added and .removed in pools so they can be iterated over
-[ ] Implement assemblages
+[x] Implement assemblages
+[x] Do :apply automatically with marked entities
+[x] Remove Entity.components. Use Entity[Component] instead
+
+[ ] Add missing documentation
+[ ] Fix current documentation
+[ ] Write unit tests
+[ ] Write examples
diff --git a/examples/assemblageTest/init.lua b/examples/assemblageTest/init.lua
new file mode 100644
index 0000000..730129b
--- /dev/null
+++ b/examples/assemblageTest/init.lua
@@ -0,0 +1,67 @@
+local Concord = require("lib").init({
+   useEvents = true
+})
+local Entity     = Concord.entity
+local Component  = Concord.component
+local System     = Concord.system
+local Assemblage = Concord.assemblage
+
+local Game = Concord.instance()
+Concord.addInstance(Game)
+
+local Legs = Component(function(e, legCount)
+   e.legCount = legCount or 0
+end)
+
+local Instinct = Component(function(e) -- luacheck: ignore
+end)
+
+local Cool = Component(function(e, coolness)
+   e.coolness = coolness
+end)
+
+local Wings = Component(function(e)
+   e.wingCount = 2
+end)
+
+
+local Animal = Assemblage(function(e, legCount)
+   e
+   :give(Legs, legCount)
+   :give(Instinct)
+
+   print("Animal")
+end)
+
+local Lion = Assemblage(function(e, coolness)
+   e
+   :assemble(Animal, 4)
+   :give(Cool, coolness)
+
+   print("Lion")
+end)
+
+local Eagle = Assemblage(function(e)
+   e
+   :assemble(Animal, 2)
+   :give(Wings)
+
+   print("Eagle")
+end)
+
+local Griffin = Assemblage(function(e, coolness)
+   e
+   :assemble(Animal, 4)
+   :assemble(Lion, coolness * 2)
+   :assemble(Eagle)
+end)
+
+
+local myAnimal = Entity()
+:assemble(Griffin, 5)
+--:apply()
+
+print(myAnimal:has(Legs))
+print(myAnimal:has(Instinct))
+print(myAnimal:has(Cool))
+print(myAnimal:has(Wings))
diff --git a/examples/simpleDrawing/init.lua b/examples/simpleDrawing/init.lua
index f9a2d9f..8cc0426 100644
--- a/examples/simpleDrawing/init.lua
+++ b/examples/simpleDrawing/init.lua
@@ -78,7 +78,7 @@ end
 function RandomRemover:update(dt)
    self.time = self.time + dt
 
-   if self.time >= 0.5 then
+   if self.time >= 0.05 then
       self.time = 0
 
       if self.pool.size > 0 then
@@ -95,7 +95,7 @@ Game:addSystem(RandomRemover(),     "update")
 Game:addSystem(RectangleRenderer(), "draw")
 Game:addSystem(CircleRenderer(),    "draw")
 
-for i = 1, 100 do
+for _ = 1, 100 do
    local e = Entity()
    e:give(Position, love.math.random(0, 700), love.math.random(0, 700))
    e:give(Rectangle, love.math.random(5, 20), love.math.random(5, 20))
@@ -107,7 +107,7 @@ for i = 1, 100 do
    Game:addEntity(e)
 end
 
-for i = 1, 100 do
+for _ = 1, 100 do
    local e = Entity()
    e:give(Position, love.math.random(0, 700), love.math.random(0, 700))
    e:give(Circle, love.math.random(5, 20))
diff --git a/lib/assemblage.lua b/lib/assemblage.lua
new file mode 100644
index 0000000..67a1428
--- /dev/null
+++ b/lib/assemblage.lua
@@ -0,0 +1,26 @@
+--- Assemblage
+
+local Assemblage = {}
+Assemblage.__index = Assemblage
+
+function Assemblage.new(assemble)
+   local assemblage = setmetatable({
+      __assemble = assemble,
+
+      __isAssemblage = true,
+   }, Assemblage)
+
+   Assemblage.__mt = {__index = assemblage}
+
+   return assemblage
+end
+
+function Assemblage:assemble(e, ...)
+   self.__assemble(e, ...)
+
+   return self
+end
+
+return setmetatable(Assemblage, {
+   __call = function(_, ...) return Assemblage.new(...) end,
+})
diff --git a/lib/entity.lua b/lib/entity.lua
index bfb9a07..441b9df 100644
--- a/lib/entity.lua
+++ b/lib/entity.lua
@@ -12,9 +12,8 @@ Entity.__index = Entity
 -- @return A new Entity
 function Entity.new()
    local e = setmetatable({
-      components = {},
-      removed    = {},
-      instances  = List(),
+      removed   = {},
+      instances = List(),
 
       __isEntity = true,
    }, Entity)
@@ -24,8 +23,9 @@ end
 
 local function give(e, component, ...)
    local comp = component:__initialize(...)
-   e.components[component] = comp
    e[component] = comp
+
+   e:mark()
 end
 
 --- Gives an Entity a component with values.
@@ -68,22 +68,36 @@ function Entity:remove(component)
       error("bad argument #1 to 'Entity:remove' (Component expected, got "..type(component)..")")
    end
 
-   self.removed[component] = true
+   self.removed[#self.removed + 1] = component
+
+   self:mark()
 
    return self
 end
 
---- Checks the Entity against the pools again.
--- @return self
-function Entity:apply()
-   for i = 1, self.instances.size do
-      self.instances:get(i):checkEntity(self)
+function Entity:assemble(assemblage, ...)
+   if not Type.isAssemblage(assemblage) then
+      error("bad argument #1 to 'Entity:assemble' (Assemblage expected, got "..type(assemblage)..")")
    end
 
-   for component, _ in pairs(self.removed) do
-      self.components[component] = nil
+   assemblage:assemble(self, ...)
+
+   return self
+end
+
+function Entity:mark()
+   for i = 1, self.instances.size do
+      self.instances:get(i):markEntity(self)
+   end
+end
+
+function Entity:apply()
+   for i = 1, #self.removed do
+      local component = self.removed[i]
+
       self[component] = nil
-      self.removed[component] = nil
+
+      self.removed[i] = nil
    end
 
    return self
@@ -107,7 +121,7 @@ function Entity:get(component)
       error("bad argument #1 to 'Entity:get' (Component expected, got "..type(component)..")")
    end
 
-   return self.components[component]
+   return self[component]
 end
 
 --- Returns true if the Entity has the Component.
@@ -118,7 +132,7 @@ function Entity:has(component)
       error("bad argument #1 to 'Entity:has' (Component expected, got "..type(component)..")")
    end
 
-   return self.components[component] ~= nil
+   return self[component] ~= nil
 end
 
 return setmetatable(Entity, {
diff --git a/lib/init.lua b/lib/init.lua
index 76f2588..81887fb 100644
--- a/lib/init.lua
+++ b/lib/init.lua
@@ -22,7 +22,7 @@ local Concord = {
 
       The above copyright notice and this permission notice shall be included
       in all copies or substantial portions of the Software.
-      
+
       THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
       OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
       MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
@@ -39,10 +39,11 @@ local Concord = {
 -- }
 -- @return Concord
 function Concord.init(settings)
-   Concord.entity       = require(PATH..".entity")
-   Concord.component    = require(PATH..".component")
-   Concord.system       = require(PATH..".system")
-   Concord.instance     = require(PATH..".instance")
+   Concord.entity     = require(PATH..".entity")
+   Concord.component  = require(PATH..".component")
+   Concord.system     = require(PATH..".system")
+   Concord.instance   = require(PATH..".instance")
+   Concord.assemblage = require(PATH..".assemblage")
 
    if settings and settings.useEvents then
       Concord.instances = {}
diff --git a/lib/instance.lua b/lib/instance.lua
index f4d63a0..fa59c35 100644
--- a/lib/instance.lua
+++ b/lib/instance.lua
@@ -2,8 +2,6 @@
 
 local PATH = (...):gsub('%.[^%.]+$', '')
 
-local Entity = require(PATH..".entity")
-local System = require(PATH..".system")
 local Type   = require(PATH..".type")
 local List   = require(PATH..".list")
 
@@ -17,8 +15,9 @@ function Instance.new()
       entities = List(),
       systems  = List(),
       events   = {},
+
+      marked   = {},
       removed  = {},
-      toRemove = nil,
 
       __isInstance = true,
    }, Instance)
@@ -43,6 +42,29 @@ function Instance:addEntity(e)
    return self
 end
 
+--- Marks an Entity as removed from the Instance.
+-- @param e The Entity to mark
+-- @return self
+function Instance:removeEntity(e)
+   if not Type.isEntity(e) then
+      error("bad argument #1 to 'Instance:removeEntity' (Entity expected, got "..type(e)..")", 2)
+   end
+
+   self.removed[#self.removed + 1] = e
+
+   return self
+end
+
+function Instance:markEntity(e)
+   if not Type.isEntity(e) then
+      error("bad argument #1 to 'Instance:markEntity' (Entity expected, got "..type(e)..")", 2)
+   end
+
+   self.marked[#self.marked + 1] = e
+
+   return self
+end
+
 --- Checks an Entity against all the systems in the Instance.
 -- @param e The Entity to check
 -- @return self
@@ -58,34 +80,33 @@ function Instance:checkEntity(e)
    return self
 end
 
---- Marks an Entity as removed from the Instance.
--- @param e The Entity to mark
--- @return self
-function Instance:removeEntity(e)
-   if not Type.isEntity(e) then
-      error("bad argument #1 to 'Instance:removeEntity' (Entity expected, got "..type(e)..")", 2)
-   end
-
-   self.removed[#self.removed + 1] = e
-
-   return self
-end
-
 --- Completely removes all marked Entities in the Instance.
 -- @return self
 function Instance:flush()
-   while #self.removed > 0 do
-      self.toRemove = self.removed
+   while #self.marked > 0 do
+      local marked = self.removed
       self.removed  = {}
 
-      for i = 1, #self.toRemove do
-         local e = self.toRemove[i]
+      for i = 1, #marked do
+         local e = marked[i]
+
+         e.instances:apply()
+         e.instances:checkEntity(e)
+      end
+   end
+
+   while #self.removed > 0 do
+      local removed = self.removed
+      self.removed  = {}
+
+      for i = 1, #removed do
+         local e = removed[i]
 
          e.instances:remove(self)
          self.entities:remove(e)
 
-         for i = 1, self.systems.size do
-            self.systems:get(i):__remove(e)
+         for j = 1, self.systems.size do
+            self.systems:get(j):__remove(e)
          end
 
          self:onEntityRemoved(e)
@@ -93,7 +114,9 @@ function Instance:flush()
    end
 
    for i = 1, self.systems.size do
-      self.systems:get(i):flush()
+      local system = self.systems:get(i)
+      system:flush()
+      system:clear()
    end
 
    return self
@@ -250,12 +273,12 @@ end
 
 --- Default callback for adding an Entity.
 -- @param e The Entity that was added
-function Instance:onEntityAdded(e)
+function Instance:onEntityAdded(e) -- luacheck: ignore
 end
 
 --- Default callback for removing an Entity.
 -- @param e The Entity that was removed
-function Instance:onEntityRemoved(e)
+function Instance:onEntityRemoved(e) -- luacheck: ignore
 end
 
 return setmetatable(Instance, {
diff --git a/lib/pool.lua b/lib/pool.lua
index 5a7f44b..e7e949c 100644
--- a/lib/pool.lua
+++ b/lib/pool.lua
@@ -36,7 +36,7 @@ end
 -- @return True if the entity is eligible, false otherwise
 function Pool:eligible(e)
    for _, component in ipairs(self.filter) do
-      if not e.components[component] or e.removed[component] then
+      if not e[component] or e.removed[component] then
          return false
       end
    end
diff --git a/lib/system.lua b/lib/system.lua
index 7c7b22a..a42f79b 100644
--- a/lib/system.lua
+++ b/lib/system.lua
@@ -2,8 +2,7 @@
 
 local PATH = (...):gsub('%.[^%.]+$', '')
 
-local Component = require(PATH..".component")
-local Pool      = require(PATH..".pool")
+local Pool = require(PATH..".pool")
 
 local System = {}
 System.mt    = {
@@ -47,11 +46,11 @@ end
 --- Builds a Pool for the System.
 -- @param baseFilter The 'raw' Filter
 -- @return A new Pool
-function System:__buildPool(baseFilter)
+function System:__buildPool(baseFilter) -- luacheck: ignore
    local name   = "pool"
    local filter = {}
 
-   for i, v in ipairs(baseFilter) do
+   for _, v in ipairs(baseFilter) do
       if type(v) == "table" then
          filter[#filter + 1] = v
       elseif type(v) == "string" then
@@ -66,8 +65,6 @@ end
 -- @param e The Entity to check
 -- @return True if the Entity was added, false if it was removed. Nil if nothing happend
 function System:__check(e)
-   local systemHas = self.__all[e]
-
    for _, pool in ipairs(self.__pools) do
       local poolHas  = pool:has(e)
       local eligible = pool:eligible(e)
@@ -76,13 +73,11 @@ function System:__check(e)
          pool:add(e)
          pool.added[#pool.added + 1] = e
 
-         self:entityAddedTo(e, pool)
          self:__tryAdd(e)
       elseif poolHas and not eligible then
          pool:remove(e)
          pool.removed[#pool.removed + 1] = e
 
-         self:entityRemovedFrom(e, pool)
          self:__tryRemove(e)
       end
    end
@@ -96,12 +91,10 @@ function System:__remove(e)
          if pool:has(e) then
             pool:remove(e)
             pool.removed[#pool.removed + 1] = e
-            self:entityRemovedFrom(e, pool)
          end
       end
 
       self.__all[e] = nil
-      self:entityRemoved(e)
    end
 end
 
@@ -110,7 +103,6 @@ end
 function System:__tryAdd(e)
    if not self.__all[e] then
       self.__all[e] = 0
-      self:entityAdded(e)
    end
 
    self.__all[e] = self.__all[e] + 1
@@ -124,13 +116,11 @@ function System:__tryRemove(e)
 
       if self.__all[e] == 0 then
          self.__all[e] = nil
-         self:entityRemoved(e)
       end
    end
 end
 
-function System:flush()
-   self:clear()
+function System:flush() -- luacheck: ignore
 end
 
 function System:clear()
@@ -147,44 +137,22 @@ end
 
 --- Default callback for system initialization.
 -- @param ... Varags
-function System:init(...)
-end
-
---- Default callback for adding an Entity.
--- @param e The Entity that was added
-function System:entityAdded(e)
-end
-
---- Default callback for adding an Entity to a pool.
--- @param e The Entity that was added
--- @param pool The pool the Entity was added to
-function System:entityAddedTo(e, pool)
-end
-
---- Default callback for removing an Entity.
--- @param e The Entity that was removed
-function System:entityRemoved(e)
-end
-
---- Default callback for removing an Entity from a pool.
--- @param e The Entity that was removed
--- @param pool The pool the Entity was removed from
-function System:entityRemovedFrom(e, pool)
+function System:init(...) -- luacheck: ignore
 end
 
 -- Default callback for when the System is added to an Instance.
 -- @param instance The Instance the System was added to
-function System:addedTo(instance)
+function System:addedTo(instance) -- luacheck: ignore
 end
 
 -- Default callback for when a System's callback is enabled.
 -- @param callbackName The name of the callback that was enabled
-function System:enabledCallback(callbackName)
+function System:enabledCallback(callbackName) -- luacheck: ignore
 end
 
 -- Default callback for when a System's callback is disabled.
 -- @param callbackName The name of the callback that was disabled
-function System:disabledCallback(callbackName)
+function System:disabledCallback(callbackName) -- luacheck: ignore
 end
 
 return setmetatable(System, {
diff --git a/lib/type.lua b/lib/type.lua
index 204aa79..80d14b0 100644
--- a/lib/type.lua
+++ b/lib/type.lua
@@ -16,4 +16,8 @@ function Type.isInstance(t)
    return type(t) == "table" and t.__isInstance
 end
 
-return Type
\ No newline at end of file
+function Type.isAssemblage(t)
+   return type(t) == "table" and t.__isAssemblage
+end
+
+return Type
diff --git a/main.lua b/main.lua
index c809a1f..ce78707 100644
--- a/main.lua
+++ b/main.lua
@@ -1,4 +1,4 @@
 local file = "examples.simpleDrawing"
 -- local file = "examples.baseLayout.main"
 
-require(file)
\ No newline at end of file
+require(file)